Tilt-in-space or tilt-and-recline wheelchairs are known. See, for example, the survey article titled xe2x80x9cTilt and Recline: A Balance of Cost and Consumer Needxe2x80x9d, which appeared in Team Rehab Report, Miramar Communications, Inc., April, 1996 (ISSN 1053-5926). A consensus of opinion in the design of such chairs appears to indicate that cost and mechanical adaptability are key factors needing improvement to satisfy current needs of patients who require such chairs for mobility.
Wheelchair bound patients, who spend most of their day in fixed-in-space seating, or in seating having limited ability to recline, can develop body sores, aches and pains and general malaise resulting from the pressure of sitting in a single position for extended periods of time. xe2x80x9cTilt-in-spacexe2x80x9d is an option that is available on some higher priced wheelchairs that allows the frame and attached seating system to be tilted or rotated in space. This is often needed to better position a patient who is hypotonic by allowing gravity to help keep him/her sitting upright. This feature is also often used in reducing sitting pressures by tilting and thus transferring pressure from the seat surface to the back surface in an effort to prevent decubitus ulcers in patients who cannot otherwise effect weight shifts.
Problems associated with current tilt-in-space wheelchairs may include:
Inability to fold the wheelchair in the conventional way for transport in a vehicle;
High cost; and
Weight.
Previous efforts have been made to provide wheelchair assemblies having adjustable seating which are also economically feasible, and are described in previous patents. For example, U.S. Pat. No. 5,292,144 describes a conversion kit for standard wheelchairs whereby a wheelchair with a stationary fixed seat can be retrofitted with a tiltable seat having a reclinable back. The seat and back may be separately adjusted by extendible, lockable adjusters and the seat and back apparatus is mountable upon conventional wheelchair constructions. See also the patents described therein. The apparatus of that invention must be removed in order to transport the chair from one site to another, and must be reassembled at the new location.
U.S. Pat. No. 4,565,385 discloses a tiltable supporting wheelchair having a tilting mechanism with front support wheels which pivot downwardly and outwardly engaging the floor and raising the front of the wheelchair, thereby tilting it backwardly. The tilting mechanism includes a cross-frame pivotably attached to the frame of the wheelchair and activated by movement of an attached arm. The arm is controlled by a rod leading to a pivotable plate which is connected to a lever on the side of the wheelchair by a linkage. Upon movement of the lever, the linkage rotates the plate, moving the arm and cross-frame to extend or retract the front wheels. A locking mechanism prevents accidental movement of the lever. Rear supports extend behind the wheelchair and engage the floor upon the front wheels being pivoted to their furthest point forward. This device also must be disassembled for transporting it from one site to another. Furthermore, when the tilt feature of this device is activated, the legrests simultaneously elevate, resulting in knee extension which is undesirable in most situations. The general purpose of a xe2x80x9ctilt-in-space xe2x80x9d chair is to rotate the patient posteriorly while at the same time maintaining 90 degree angles at the hips and knees. This prior apparatus does not maintain all relative positioning angles of the patient""s body and limbs upon tilting of the chair.
An improved, manually propelled, tilt-in-space wheelchair is provided. A patient seated in the wheelchair may be tilted backwardly or forwardly so as to rotate the patient spatially while maintaining all relative positions of the patient""s body and limbs fixed with respect to one another. The wheelchair is of the folding type having an X-brace frame mechanism which permits the unoccupied wheelchair to be folded side-to-side for ease of transport from one site to another. The wheelchair has conventional, large, paired drive wheels, and paired smaller, independently castered front wheels. The patient seating apparatus is supported by a support frame mounted on the axle, and includes seat, back, a headrest, legrests and armrests.
In its most general form, the wheelchair of the invention includes means for effecting rotation of the entire patient seating apparatus, including the patient seated thereon, about the axles of the large wheels, while maintaining the drive wheels and the front castered wheels all in fixed spatial relationship, i.e. resting on a fixed ground plane, with respect to each other. The chair also includes means for locking in place the patient seating apparatus at any desired rotation. A key feature of the present invention, and essential to the improvement provided, resides in the fact that the means for rotating the patient and the means for locking the apparatus at the desired rotation do not interfere with nor inhibit the ability of the chair to be folded, side-to-side, for transport.
In one embodiment, discussed more fully below, the improved apparatus includes elongate supporting brace members, each having a forward end and a rearward end, the rearward end of each being affixed to the support frame in close proximity to the wheel axle, one adjacent each drive wheel, with the forward end of each having a caster housing which houses one castered front wheel. The tilt-adjusting brace members each act cooperatively with one of the supporting braces, with each tilt-adjusting brace member also being affixed to the support frame at an intermediate position between the forward and rearward ends of its cooperating support brace and in adjacent proximity thereto. Means are provided for effecting relative movement of each tilt-adjusting brace member relative to its cooperating supporting brace so as to effect rotation of the patient seating apparatus about the wheel axles, and for locking the supporting braces in fixed positional relationship with respect to the tilt-adjusting brace members at a desired extent of rotation.
The tilt-adjusting brace members may each have arcuate, rearward edges possessing gear-like teeth therein, these arcuate edges being concave with respect to the axle and substantially concentric with respect thereto. The means for locking includes spring-biased tooth engaging means affixed to the supporting braces which releasably engage the gear-like teeth at the desired rotation and effect locking of the patient seating apparatus thereat.
In an alternate embodiment, the locking means include cam-actuated means for engaging and disengaging locking at any desired degree of spatial rotation of the chair, also by means of spring-biased tooth-engaging means.
The wheelchair may include a manually operated lever control mounted so as to be gripped by an attendant pushing the wheelchair and having flexible cable means mounted on the frame rearwardly of the patient. The cable preferably extends from the lever to the spring-biased tooth engaging locking means, providing manual control of the locking of the seating apparatus at the desired extent of rotation. Additional, independently adjustable means for spatially varying and adjusting each of the seat, back, headrest, legrests and armrests may be provided.